message_router.h

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.// Use of this source code is governed by a BSD-style license that can be// found in the LICENSE file.#ifndef CHROME_COMMON_MESSAGE_ROUTER_H__#define CHROME_COMMON_MESSAGE_ROUTER_H__#include "base/id_map.h"#include "ipc/ipc_channel.h"// The MessageRouter handles all incoming messages sent to it by routing them// to the correct listener. Routing is based on the Message's routing ID.// Since routing IDs are typically assigned asynchronously by the browser// process, the MessageRouter has the notion of pending IDs for listeners that// have not yet been assigned a routing ID.//// When a message arrives, the routing ID is used to index the set of routes to// find a listener. If a listener is found, then the message is passed to it.// Otherwise, the message is ignored if its routing ID is not equal to// MSG_ROUTING_CONTROL.//// The MessageRouter supports the IPC::Message::Sender interface for outgoing// messages, but does not define a meaningful implementation of it. The// subclass of MessageRouter is intended to provide that if appropriate.//// The MessageRouter can be used as a concrete class provided its Send method// is not called and it does not receive any control messages.class MessageRouter : public IPC::Channel::Listener,
public IPC::Message::Sender {
public:
MessageRouter() {}
virtual ~MessageRouter() {}
// Implemented by subclasses to handle control messagesvirtualvoid OnControlMessageReceived(const IPC::Message& msg);
// IPC::Channel::Listener implementation:virtualvoid OnMessageReceived(const IPC::Message& msg);
// Like OnMessageReceived, except it only handles routed messages. Returns// true if the message was dispatched, or false if there was no listener for// that route id.virtualbool RouteMessage(const IPC::Message& msg);
// IPC::Message::Sender implementation:virtualboolSend(IPC::Message* msg);
// Called to add/remove a listener for a particular message routing ID.void AddRoute(int32 routing_id, IPC::Channel::Listener* listener);
void RemoveRoute(int32 routing_id);
IPC::Channel::Listener* ResolveRoute(int32 routing_id);
private:
// A list of all listeners with assigned routing IDs.
IDMap<IPC::Channel::Listener> routes_;
DISALLOW_COPY_AND_ASSIGN(MessageRouter);
};
#endif // CHROME_COMMON_MESSAGE_ROUTER_H__